The invention relates generally to a system and method for controlling an engine driving a generator through the use of control circuitry that integrates control functions of both the engine and the generator.
Engine-driven generators are commonly used to provide electrical power in locations where conventional electrical power is not readily available. Both gasoline and diesel engines are used to drive such generators, and the power produced is typically either 120 VAC or 240 VAC. An engine-driven generator may be used to supply power to a welding gun (e.g., torch, arc, or the like) for applications such as, for example, stick electrode welding, MIG welding, TIG welding, etc. These welding systems include a control system to regulate the power produced by the generator, thereby making it suitable for arc welding, plasma cutting, and similar operations.
Typical welding systems offer the user little customizable control over the engine settings. For example, the engine may employ an engine governor to control the engine speed. When the welding gun or an auxiliary device is connected to the system and turned on, the engine speed may increase to the speed required to power the load. This speed increase may be determined by a generic governor curve which slowly increases the engine speed to substantially prevent overshooting the required speed. No distinction is made between the weld load and the auxiliary load, such as a light, which may require significantly less power to operate than the welder.
In addition, during periods of non-use of the typical welding system, the engine speed may be reduced to an idle speed. However, this idle speed may still consume a great deal of energy and produce substantial noise levels. A user may have no choice but to endure these inconveniences or to manually turn the engine off when it will not be used for some time. The engine must then be manually restarted before the welding gun may be used again.
One reason for such limited control options has been the virtually completely separate design and configuration of engines and the generator systems that they ultimately drive in such applications. In general, engines are designed for a wide range of applications, and whether controlled by mechanical or electronic means, typically self regulate based upon known speed, torque and power relationships, and knowledge of factors such as fuel flow rates needed to produce desired speeds. At the same time, generator system manufactures typically design separate controls that regulate output of the generators in response to demand, and that at best provide inputs to the engine controller. However, little additional coordination in control is typically provided.